Temporary protective coating



Patented July 7, 1936 UNITED STATES PATENT OFFICE TEMPORARY PROTECTIVE COATING No Drawing. Application February 9. 1935 Serial No. 5,864

Claims. (01. 36-72) .This'invention relates to temporary protective coatings, and it comprises an article of manufacture, such as a. shoe or part of a shoe, covered by a temporary protective coating formed in 6 situ and composed of an outer coating'of cellulosiccomposition normally tending to adhere to said article but having its adherence diminished by an intermediate coating, usually of powdery nature, having but little adhesion to said ar- 10 ticle; and it also includes a process of temporarily protecting an article of manufacture which comprises applying thereto a non-adherent coating, applying over said coating a film-forming cellulosic composition, allowing said composition to dry and harden and thereafter removing the resultant coating, preferably by means of an air blast; all as more fully hereinafter set forth and as claimed. A

There is an important demand in various industries for temporary protective coatings, for example to be applied to articles of manufacture during certain stages of processing. Many such articles are subject to injury or soiling or 'by handling prior to packaging. In the boot and shoe industry, for example, it is quite essential that light colored leathers be protected from soiling and marring during certain operations of manufacture. The use of various types of protectors has become conventional in this art and a large number of patents have been issued for various devices for temporarily covering parts of shoes during manufacture.

The cloth or leather protectors which are in common use today are not particularly satisfactory. These protectors become soiled in time and they are troublesome to put on and to take off. They are bulky and appreciably increase the weight of the shoes to which they are applied.

While it has been proposed from time to time to employ various coating compositions, such as celluloidvarnish; latex or gelatine, as single-temporary protective coats, these methods have not been adopted in the industry. Such coatings are diillcult to remove. When dissolved of! with solvents a sticky surface is left upon which dust and dirt rapidly collect. If bufllng with a wire brush or the like is resorted to for removal of such temporary coatings the leather beneath the coating is likely to be damaged before all particles of the coating are removed.

We have found that if articles of manufacture, such as shoes, for example, are initially coated with a composition which is non-adherent or only slightly adherent to said articles and thereafter a film-forming coating of cellulosic composition is applied over said initial or prime coating, the protective coating can later be readily and quickly removed. We have further found that this protective coating can usually be removed by use of an air blast. 5

In practice the initial or under-coating can be of a nature tending to preserve or improve the article of manufacture to which it is applied. A. masking paste can be applied to leather articles, for example, and when the outer coating of cellul0 losic composition is removed, the article is then in perfect condition for-finishing.

We usually find it'advantageous to use an undercoating which will dry to form a layer of powdery nature. Specific compositions of this 15 general type are (1) bentonite with suflicient water to make a paste and to which a small amount (2 to 4 per cent) of magnesia may be added if desired, (2) a mixture of glycerine, water and pumice in paste form and (3) prepared chalk 2o or talc with water and a small amount of an adhesive agent such as starch or flour. Many of the preprations on the market for cleaning light colored shoes and which are put up in liquid or paste form can be used, provided they form a powdery coating when dried. In the case of these preparations,- after. removal of the outer coating, a small amount of the cleaner frequently remains on the shoe. This may be removed by means of a wet sponge, for example, cleaning of the shoe taking place incidentally.

All compositions of this general nature, when applied to an article and dried for a short time, form a thin, rather brittle layer of powdery nature', being highly absorbent. When a fllm-forming cellulosic composition is applied to this undercoating there is some penetration. The lacquer keys to the under-coating to a degree and, when the coating has dried, if punctured or slit, the whole can be removed by a simple stripping or peeling process or more advantageously by means of an air blast. The powdery layer adjacent the surface of the article appears to permit penetration of air between the coating and the surface of the article. The coating is thus raised from the surface of the article and removal is readilyaccomplished.

In this manner there is formed a protective layer of substantial thickness which willwithstand rough usage without injury to the surface beneath. When this layer is once perforated, however, it can be readily removed as stated.

Compositions satisfactory for the outer-coating are of widely varying types. Our tests indicate that all quickly drying film-forming cellulosic compositions are suitable. This includes solutions of cellulosic esters and others and regenerated cellulose which may or may not be modified by the addition of resins, plasticizers, softeners,-

high boilers and other modifying ingredients. Viscose, 'cellulose nitrates, and cellulose acetates are specific examples. Any of the nitro-cellulose cements, collodion or celluloid varnishes, etc., produce good results, provided they are quick drying. The cellulosic composition should have a highly fluid consistency and yet have a high solid content. Otherwise two coatings of this material may be required.

In a specific embodiment of our invention, which represents an actual commercial operation, we took several pairs of white shoes during the course of their manufacture and. directly after the lasting operation we sprayed them with a light coating of a .preparation having approximately the following composition:

Per cent Talc 40 to '50 Glycerine 30 to 40 Water 10 to 20 This under-coating was air dried and directly afterwards we applied a second coating by spraying a simple solution of cellulose acetate (about one-half pound of cellulose acetate dissolved in a gallon of solvents).

This second coating was also air dried. The

shoes were then put through the regular manufacturing steps following lasting without the use of any of the usual protectors. When the mechanical operations were completed the lacquer coating was slit with a knife and an air blast applied at this point. readily blown off, using about '75 pounds air pressure in the blast. The time taken for removal of the coating was not over 15 seconds. The leather was found to be in perfect condition. The usual cleaning operation was eliminated and the shoes were then passed directly to the finishing steps.

The protection of .the shoes is so perfect by our method that we have found that the leather can be partially finished after lasting and before application of our protective coating. Or the leather itself prior to dyeing can be coated by our method, and after our coatings are removed the leather is in a condition to be dyed. During the manufacturing steps the coating may become damaged to some extent but not sufficiently to impair its protective functions.

While we have described what we consider to be the best embodiments of our invention, it is obvious that many modifications can be made which fall within the spirit and scope thereof. Our process is especially useful in the manufacture of all types of leather goods such as shoes, pocketbooks, bags, gloves, etc. Various methods of applying the coatings of our invention may be used, such as dipping, spraying, brushing and the like.

The whole coating was Our invention may be used in the case of all articles of leather where temporary protection is required for any purpose. The coating of our invention can also be used where semi-permanent but easily removable wrappings are desired. Ex- 5 amples of articles which can be thus covered are pocketbooks, etc. The cellophane wrappings now so commonly employed on manufactured articles can be largely replaced by our coatings, provided the surface of the article is smooth and if an under-coating is available which will not damage the article but which will successfully prevent adhesion of the second coating to the article. Other modifications which fall within the scope of the following claims will be immediately evident to the art.

From the foregoing it will be seen that our invention consists in applying a cellulosic composition to the article without said composition making contact with said article by reason of an intermediate coating, whereby the protective film-forming properties of a cellulosic composition may be taken advantage of, without, however, said composition becoming part of the article.

' We claim:

1. An article of .leather covered by a two-layer temporary protective coating, the under-coating consisting of a composition of powdery nature, and the outer-coating being a film of cellulose ester composition, the coatings being readily removable by stripping, air blasting, and the like.

2. A process of temporarily protecting articles of leather which comprises applying to such articles a two-layer protective coating consisting of an initial coating of powdery nature having but slight adhesion thereto, and a film-forming outer coating of cellulosic composition.

3. The process which comprises applying to a shoe during the course of its manufacture a powdery under-coating and a film-forming outercoating of cellulosic composition and later removing the said coatings by means of an airblast after the manufacturing operations are completed.

4. The process which comprises lasting a shoe, applying an under-coating of powdery nature and an outer-coating of cellulosic composition, completing the manufacturing operations and stripping the coatings by means of an air blast.

5. The process which comprises applying to a shoe during the course of its manufacture a coating of, an aqueous suspension of a material of powdery nature. air drying said coating, applying thereover a film-forming cellulosic composition, then continuing the manufacturing operations, stripping the coating by means of an air blast and wiping the shoe with a wet sponge to remove said material of powdery nature.

6. The process of claim 2 followed by remov ing the protective coating by puncturing and stripping with an air blast.

GRAYLE W. HOWLETI'. WEI-1AM E. HALL. 

